code: def header(key, request):
      key = key.replace("_", "-").encode("utf-8")
      headers_dict = dict(request.scope["headers"])
      return headers_dict.get(key, b"").decode("utf-8")
  
file_path: datasette/datasette/default_magic_parameters.py
imports: from datasette import hookimpl
  import datetime
  import os
  import time
label_desc: Use image node_id 1 for calling a global function with example usage: header(key, request) and returns: headers_dict